What happens to the focal length of a lens when it is immersed in water?
Correct Answer: Focal length decreases.
- Step 1: Understand what focal length is. Focal length is the distance from the lens where light rays converge to a point.
- Step 2: Know that lenses bend light. The amount they bend light depends on the lens material and the surrounding medium.
- Step 3: Recognize that air has a lower refractive index than water. Refractive index is a measure of how much light bends in a material.
- Step 4: When a lens is in air, it has a certain focal length. This is based on the difference in refractive index between the lens and air.
- Step 5: When the lens is placed in water, the surrounding medium (water) has a higher refractive index than air.
- Step 6: Because of this change, the lens bends light less when in water compared to when it is in air.
- Step 7: As a result, the focal length of the lens decreases when it is immersed in water.
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